THE HORMONES IN HUMAN REPRODUCTION 



adequate substitute for what the animal's own ovaries pro- 

 duce. 



Probable daily output of estrogenic hormone by the mon- 

 key. By all these means of estimation we arrive at the result 

 that the probable daily output of estrogenic hormone by the 

 young adult Rhesus monkey is equivalent to somewhat more 

 than 150 international units and may be set tentatively at the 

 equivalent of 200 international units of estrone. This is a 

 minimum figure; the true amount may be greater, but can 

 hardly be smaller. 



This estimate is based necessarily on the assumption that 

 an ovarian hormone injected once daily in oil solution is 

 utilized by the body as efficiently as hormone produced in the 

 animal's own ovaries. There is at present no way of ascertain- 

 ing how nearly this is true, but in any case, the slow absorp- 

 tion of an oily solution must afford a fairly good imitation of 

 natural processes, and we may recall that my estimate of the 

 rate of secretion of progesterone, which involved the same 

 assumption, turned out to be near the truth, when checked by 

 the recovery of the excretion product, pregnanediol. 



Administration of estrogenic hormone in pellets. In recent 

 years many experimental workers have been administering 

 estrogenic hormones by compressing them into small hard 

 pellets which are buried under the skin. This method has the 

 advantage that the hormone is absorbed continuously from 

 the surface of the pellet, whereas when given by injection the 

 rate of absorption fluctuates, being high just after an injec- 

 tion and lower as more and more of the injected dose is ab- 

 sorbed. For this reason a given effect is obtained from a 

 smaller daily dose when absorbed from a pellet than when 

 injected. Pellets will probably be used in human cases in which 

 long continued action is required, not only because of the 

 continuous absorption, but also because insertion of the pellet, 

 which can be done through a hollow needle, avoids repeated 

 hypodermic punctures. 



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